Telephone-exchange system



'June 8 1926. ,587,620

- J. F. TooMEY TELEPHONE EXCHANGE SYSTEM Filed June 13,. 1924 4 sheets-sheet 1 June 8,1926.

J. F. TOOMEY i'vIELEPI'IQNE EXCHANGE SYSTEM 4 Sheets-Sheet 2 /f/z/e/I/a/- dM/l Home] Filed June 14, 1924 NWN. RN,

www QQ @N N www@ June 8 9 926 ,58\7,620

i J. F. TOOMEY TELEPHONE EXCHANGE SYSTEM4 Filed June 14, 1924 4 sheets-sheet 3 W5 wy June 8 1926.

J. F. TCOMEY TELEPHONE EXCHANGE SYSTEM Filed June 14. 1924 4 Sheets-Sheet 4 @E y@ S p QW w 1% m Ms QQ WELT@ Jl Nwml L. QQ

t i gim) `liateluted June it, 19226 JOHN F. TOOlVIEY, OF NEVI YORK, N. Y., ASSEGNOR TO AMERCAN TELEPHONE AND TELEGRAFH COMPANY, A CORPORATO-N OF NEV YORK.`

TELEPHONIE-EXCHANGE SYSTEM.

Application led June 14,

',lhis invention relates to telephone exchange systemsvand more particularly te circuit arrangements for enabiing` toll operators to build up toll connections with auto- Vmatic subscribers lines.

The object ot this .invention is to improif'e the operating elliciency of, and effect equipment economies in, circuits of this character.

A feature of the invention resides in supplying;` the dialingij current from the operators dialing circuit at the outgoing` end ot the toll switching trunk and receiving; and translating this current at the distant or machine switching' end oi the trunk into the usual pulses Yfor setting; the switches ther-eat, whereby a normally dry (i. e., battery tree) trunk is secured.

A more speci tic feature to the above resides iu providing pulsing' and cutdhrough equipment at the incoming' or Liachine switching' end ot the trunk circuit, which includes a pulsing` relay bridged across the trunk which is controlled by the operatoi"s dialing battery and which, in turn, controls the pulsing' relays of the automatic switches.

@ther features will appear hereinafter.

lte'lierrinp,l to the drawings, Figure 1 shows a toll cord circuit, an operators telephone circuit and associated dialing' equipment.

Fie'. 2 shows at the lett of the broken line AA. an outgoing trunk circuit to machine switching' oiiice, between the brolren lines AA and BB the pulse translating equipment at the machine switching' ohce, and to the right of the broken line BB an incoming selector.

Figi'. 3 shows` a toll transmission selector and Fig. 1 shows a toll connector.

.ln general in the system of this invention the toll operators position is provided with a number oi toll cords similar to that shown in Figa'. 1 and with the telephone and dialing circuit also shown in Fig. 1 which is common to all these toll cords. lVhen the operator desires to build up a toll connection she inserts plug 100 in the jack 200 oi' an idle outgoing toll switching' trunk leading' to the desired machine switching;` oilice and actuates the dialing); key 107 of the toll cord taken ior use. This key when operated com pletes a circuit 'for relay 10G in the toll cord which was prepared. by the operation oi'. relay 103 when the plug' was inserted in the jacl: 200. Relay 106, in operating', disconnects the calling` plug 100 from the remain- 1924. serial No. 720,084.`

der of the cord circuit and connects the common dialing circuit shown in the upper half of Fig. 1.to the calling plug. The operation oi relay 106 closes a circuit for relay 108 oi the dialing` circuit which is completed through relay 202 2) at the machine switchingtgj oiiice, both of which relays operate in series with battery associated with the dial. Relay 202 in operating connects a bridge including;y resistance 207 across the tip and ring conductors 226 and 230 leading' to the incoming selector shown to the right of the broken line BB', thus starting its. operation pie paratory to receiving the pulses. Relay 10S extends the ground supplied from the dialing' liey to relay 115 thereby causing its operati-on, which in turn, supplies ground to hold both itseliA and relay4 100 operatedV independent o'l" the dial key 107 which can now be released.

VVilhcn the dial 109 is moved oil-normal relay 116 is operated, thus breaking;` the circuit for relay 105 and preventing the premature release o1E the 'dial circuit when relay 108 releases asit follows the dial pulses. Relay 116 also furnishes ground to hold relay 115 operated until the dial returns to normal. Y

fis the dial returns to normal relay 202 of the pulsing circuit (Fig. 2) Yfollows the pulses, thereby alternately making and breaking the bridge across the tip and ring` conductors leadingl to the incoming selector, which selector is actuated in response to these pulses in the usualV manner. paths busy or line busy is encountered or iii the called line is seized, ground is' connected to the conductor 222, whichk causes the operation oi" the relay 208, which momentarily opens the circuit for relay 108 in the dialing circuit, which relay falls oli and lcloses a circuit for relay 105 which operates and removes battery from relay 106, thereby causing); its release. The disconnection of the dial circuit from the cord restores the continuity oi' the cord circuit.

At the machine switching;` oiiice when relay 208 operated and relay 202 released, the bridge across the conductors 226 and 230 leading to the incoming selector was opened at the alternate contacts oi" relay 202, but this bridge was closed when relay 208 operated so that the selector was not aiieeted. Relay 208 in operating also closes a circuit 'for relay 214 which relay, in operating,

caused relay 203 "to operate. When relay 203 operated it locked up to 'the connector' 222 and at the same time opened the energizing circuit for relay 208, thereby alloW- Y ing it to release. 'Ytlhenfrelay 203'operated it disconnected the pulsing relay 202 and extended the tip and ring conductors-of the trunk through to the incoming selector, and a supervisory signal l'Will :thereafter come back over .the tip and ring conductors of the trunk to operate the calling supervisory vrelay 118 and calling supervisory lamp 119 associated With the cerdcircuit in 'the usual manner.

Having described ina brief Waythe operation of the system embodying the present inventionfa more detailed description -Will now be given. The tdll operatorhavingreceived the number or the desired station from the recording operator-or in any other suitable manner touches'thetip other plug 100, to the sleeve of jack 200 yto select an idle trunk leading to the machine switching oilice in which the desired line terminatesl and if it is idle inserts the plug in thejacl; of such idle trunk. A busycondition of the line is indicatedbyfbattery on the sleeve of the jack200 which produces a click in the receiver' 150 ofthe operators head set in the following manner: battery 'from the sleeve of the jack 200 over the tip of the plug 100 and upper normal contacts of relays 10G and 103 charges the condenser 151 which discharges toground through the left-hand Winding of repeating coil 152. rIhis causes an induced current to flow .in the right-hand Winding of coil 152 and a. consequent click in the receiver 150 due to the rfact that the Areceiver winding is `normally connectedfacrossthe terminals of this coil Winding.

vinsertion of the plug 100 `in an idle jack 200 completes an obvious circuit for the energization of relay 101. 'Relay V101 in operating closesan obvious circuit to operate relay 103 Which-relay at-its lower alternate contact 101lfprepares a circuit for relay 106 which is operated as soon as dial lrey 10'(- iis operated. Relay 10,6 in operating connects-the tip and `.ring conductors of the cord through tothe dialing' circuit thereby causing the Loperation of relay ,108 in the dialing circuit-and relay202 in the pulsing circuitatthe distant machine switching of- Iice. This circuit may be traced lfrom battery through resistance `11Zpu`lsing contact `109 of the dial "110, `Winding of relay 108. contacts `11:1 of relay v106, ring contacts of the :plug 100andjaclc200, contacts 204 ot relay203, contacts 205 of relay 208, winding of relay202, contacts 206 of relay 203, tip contacts of .jack .200 and plug 100, contacts 112 .of relay V106,'to ground. IRelay 202 in operating bridffge resistance 207 across the tip and ring conductors of the trunk extending `to the first or toll selector, which is shown at the right ot line BB of Fig. 2, thereby causing relay 209 to operate to prepare `this selector 'for the reception ol inipulses. Rclay 108 in operating extends the ground received 'from the dial key 10T to the ln'inding oiii'elay 115, thereby causing its operation. This circuit can be traced from -grounded battery, winding ot relay 115);

alternate contact 114 ot relay 108, alternate contacts 113 ci' relay 106 and to ground at the lower contact ot dial key '107. Relay 115 in operating supplies 'ground for itseliC at its richt-"hand alternate contact and also for relay 106 thereby making 'these relays independent oi the dial key 107. rl`he operator now turns the dial 110 to the first digit of the wanted number. l-Vhen the dial 'is moved ott' normal, relay 116 operates in an obvious circuit thereby breaking-the circuit for relay 105 and preventing the premature release of the dial circuit when relay D releases and closes its alternate cont act 'tollen'- tlie dial pulses. Relay 110 in operating-,1l also supplies ground at its left-hand alternate Contact to hold relay 1115 operated until the dial returns to normal.

the dial 110 returns to normal relay 202 of the pulsing circuit (Fig. 2) is released and energized in accordance with the opening and closing ol the dial contacts 100 thereby alternately opening and closing the bridge consisting of resist-ance 207 across the tip leading` selector to the first selector. The lfirst circuit shown at theright or' linel BB in Fig. v2 functions in the Well known manner as described in Patent 1.377,225a issued ltlay '10, 11021 to A. J. Seymour and its operation will therefore not be described in detail,'it being sullicient to mention that as the dial returnsjto normal the vertical or primary magnet PM of the selector receires impulses from the impulse relay 209 in the Well known manner and raises the selector brushes 218, 219, 220, 221 to the desired level after which the rotary or secondary magnet SM is energized and causes the brushes to yhunt :tor an idle trunk leading to the toll transmission selector (Fig. In the case or the irst selector finding all the trunks busy in the -selected group leading to the toll transmission selector' Fig. 3, sivitch 210 will be operated on the eleventh rotary step of the selector thus closing an obvious energizing circuit tor relay 211 which upon operating connects ground at its uppermost contact to the leadv222, thereby causing the operation of relay 208, a circuit for which can be traced from grounded battery through the winding off' this relay, contacts 212 of relay 203 and to ground at the uppermost contact or' relay 21-1. Relay 208 in operating opens at contacts 205 the circuit for relay 108 in the and ring' conductors of the trunk l dialing' circuit whirh relay then releases and closes at its alternate Contact the Circuit ilor the energization oit relay 105 which eireuit rau be trzuxd li 5 lett-hand alternate rentar-t olf slow-torelezule relay .15 rightehaiul winding;` olf relay i053, rigy hand normal rontaet o'll relay lill. (this relay heine' relearrsed due lo the nornlzfzl rendition ol lhe dial al this time) normal Contact olf relay llll and to ground at 'the right-hand alternate Contact ol relay llo. llolay lll'i in lperatlng opens at ils rightliand normal rou ret the energizing` Circuit 'lor relay llll which relay now releases thereliy disrouneeiug the dialing* elreuit troni the cord and restoring' the oord lo normal.

lelay 2ll in eperatiug, also reverses and reduces the current supplied to the trunk 'lrosu relay l). and at the saine time eonneets grounded interrupter 22st 'through relay 223 lo battery,v thereby musing; this relay to alternately open and close contaets 225 at-lhe rate o'lf 60 interrl ions per minute. llflieu relay 208 opera 1 it rlosed its rigrlil allernate toniaelsnvuirh prevailed the truulr bridge Ylroui heine; open when eruilaetsll were lu'olieu. lle/lay 205%. in operating9 also supplied grourul at its outer lett alternate routmfls to prepare an eueriizlrrf eirruit for relay 21T under control oli the alternately operating relay 22?, which oirruit can he trae-ed from ground 'throiugh left eontarts ol relay 208, winding); of relay 21'(7 normal. Contacts ol? relay 202. tip conductor 226 oll the trunk, contacts' 227 of relay 213, contacts 22S oli relay 2ll. roslstance 22), roulants ol relay 223 and armer winding' oli relay 209 to grounded battery.

(ln the lirst closure ot Contacts 225. relay 21.7 operates and closes an obvious energizingrr Circuit for relay 203. which relay operates and loeks to pjroluid supplied in the uppermost Contacts of relay 211. over the ronduetor 222,r

lelay 2055. in operating, disconnects the pulsing` relay 202 l'ron'i the trunlf: and opens 'the energizing: eireuit for relay 203. whieh relay now releases and removes the bridge including' resistance 207 from across the conductors 226 and 230.

'llie trunk is now out through to the lirst selector and receives the interrupted. reversed and redueed Current which is transmit-ted to the oord Circuit.` where it- Causes the alternate operation of the bridged supervisory relay 118 in the well known n anner'. which supervisory elay Causes supervisory lamp 11.9 to flash in step with interrupter 224. to indicate to the operator that a busy trunk group has lieen encountered and 'hat it will he liutile to Continue dialinu7 where upon the plus` is withdrawn and the oireuit at once restoresv to normal. lit, howeyer the first selector (lliej. an idle trunl, relay 2.13 operates and Cuts otl the bridge 'lltl of relay 32%? ron lower lerlsliand .riudiup; ot rialeatiugr eeil -ll, ring' eondurgor oli the trunk. brush eontaots 2l5 oi relay 213 conductor 29)()j i sislianre 207. alternate contarle ot relay 2( 2 conduetor 226j contacts 2id: ot relay 2li-l. lirusli 2l8 upper left-hand wint' le; of repeatiun coil '3l2, and to ground at contacts 3l?) oli relay 31.1.

)relay operates in the 1oetore traced rireuit and in attracting; its lmrerrnost arn'lature closes an obvious energizing` eireuit lor slow-to-release relay 314. Relay 314- in energizing Connects ground at its outer lett hand alternate Contact over conductor 315 to cause this trunk to test husy in the well lfuown n'ianner.

lhe second operation ol the dial causes relay 305 to transmit impulses over the :tollowing` eirouit to the vertical magnet Slo, ground. lmverinost uornial Contact olf relay 305, contacts 3l? ot relay $14-, contacts 318 olf relay 3197 windings of relay 320 and niagnet 316 to A.s rounded battery. rl`he brushes o'l the seleetor are thus elevated to the level o'l"-tlie trunks leading' to the desired eenneetor group terminal. lilllhen the dial returns to normal and maintains relay 305 energized, slow relay, 820 after a short in- 'erval releases.

llllien slow-to-release relay 320 operated on the lirst impulse and the selector took its llrst step, relay 321 operated in the tollen.'- 'ingg eireuit; battery, vinding of relay B2i, Contacts 322 or" the oll-nornial switch S22-l, eontaot-s 2d ol" relay 320y conductor 325% eont-aets 26 o1 relay 8199 conductor 3217. Contacts 828 ot relay 329,' contacts 330 ot relay 309 and contacts 331 ol relay 382 to lground. Relay 321 in ,operating looks itself up to ground at the left normal contacts 335 of relay 307. This loelrinp; eir- Cnit n'iay he traced from battery, winding of relay 321, contacts 822 ot switeh 32?. contacts 333 ol relay 332, contacts 384- ot relay 321 and to ground over contacts el' relay 307. l

Relay 32]. in operating also closes a shunt eirouit around relay 319 which can be traced as follows: ground, contacts oil' relay 307, contacts 384io relay 821, winding olE relay 319, contacts 336 of switeh 357, conductor 3d() and to ground at the right-hand alternate contacts of relay 314. Upon the cessation of the impulses and the release olf slow relay V320, the circuit ot the rotary magnet 332 is closed as follows: battery`r winding' ot relay 832, eontaets ot relay 321, contact-s 339 o relay B20, conductors CO lO 325 and 340 to ground at the right alternate contact of relay 314. The rotary magnet 332 advances the brushes to the terminals of the lirst trunk and if it is not busy no ground will be present on the sleeve terminal 362 and the locking circuit of relay 321 will therefore be opened at the contacts 333 of the rotary magnet 332 and relay 321 will release thus breaking at contacts 334, the shunt circuit around relay 319 which was applied when relay 321 operated. rl`he circuit for rotary magnet 332 is also opened at contacts 333 upon the release of relay 321. lVhen the armature of rotary magnet 332 retracts it closes a circuit for the operation of relay 319 which can be traced as follows: battery, winding of relay 321, contacts 322 of switch 323, contacts 333 of relay 332, winding of relay 319, contacts 336 of switch 337 and to ground at the righthand alternate contact of relay 314. Relay 319 alone energizes in this circuit relay 321 being` marginal and not capable of' operating in series with relay 319.

lf the first trunk is busy its sleeve termi* nal 362 will be grounded. ln this case relay 321 releases as usual upon the energization of rotary magnet 332 but relay 319 will not operate as it is still shunted by ground supplied from terminal 362 on the right normal contacts of relay 307 and contact 363 of relay 319. l/ihen the rotary magnet 332 releases, relay 321 again energizes which in turn causes magnet 332 to operate and the brushes are stepped forward to a second set of terminals. This operation is continued until an idle trunk is found.

When an idle trunk is reached, relay 319 operates as before described and extends the tip and ring conductors of the trunk to the selector brushes which are now in engagement with an idle connector (Fig. 4). Relay 319 in operating also grounds the sleeve brush 341, and consequently the test multiples of the selected trunk, thereby causing them to test busy to other selectors. This circuit can be traced .as follows: ground, right alternate contact of relay 314, conductor 340, contacts 342of relay 319, right normal contact of relay 307, and thence to brush 341 and terminal 362. Relay 319 in operating also opens at its contact 313 the circuit for vertical magnet 316.

lVhen relay 320 was first actuated relay 329 was operated over the following circuit: ground, right alternate contact of relay 314, contacts 378 of relay 320 and win-ding of relay 329 to battery. Relay 329 in operating locked up in the following circuit: battery, winding of relay 329, contacts 343 of relay 329, conductor 327, confacts 326, of relay 319, conductor 340, and right alternate contacts of relay 314 to ground. Relay 329 in operating also opens the circuits for relays 344 and 311 and contacts of relay 307, contacts 342 of relay 319, conductor 340 and to ground at the right alternate contact of relay 314.

Thus the circuit of relay 329 will be maiutained closed if the circuit is extended for a purpose which will later appear.

rlhe seizure of the trunk leading to the connector (Fig. 4) closes the following circuit for the pulsing relay 400: battery, upper winding of relay 400, upper normal contacts of relay 403, contacts 404 of relay i 402, conductor R, of the trunk, 'terminal and brush of the selector switch, contacts 351 of relay 319, contacts 352 of relay 332. lower right-hand winding of repeating coil 312, resistance 346, contacts 353 of relay l 329, winding of polarized relay 348, resistance 347, upper right-hand winding of repeating coil 312, contacts 354 of relay 332, contacts 355 of relay 305, contacts 356 of relay 319, brush and terminal of the selector switch, contacts 405 of relay 402, contacts 406 of relay 403 and to ground through the lower winding of relay 400. Relay 400 is energized in this circuit and closes a circuit for the energization of relay 407 which can be traced as follows: grounded battery, lower winding of relay 407, contacts 408 of relay 400 and to ground at contacts 409 of relay 402. Relay 407 operates and locks up at its contacts 410 to the sleeve conductor 440 which is grounded at relay 314 (Fig. 3

)The return of the dial to normal transmitting the tens digit of the wanted number interrupts the circuit for relay 202 of Fig. 2 which in turn alternately breaks and makes the bridge including resistance 207 across the trunk which in turn alternately interrupts at contacts 355 of relay 305 the circuit of relay 400. The lower armature of relay 400 therefore follows the dial pulses and in its turn transmits impulses to the vertical magnet 411. The circuit for the first impulse is as follows: ground, contacts 409 of relay 402, alternate contacts 412 of relay 400, contacts 413 of relay 407, contacts 414 of the off-normal switch 415, windingsl of slow-torelease relay 416 and Vertical magnet 411 to grounded battery. The of`f-normal switch 415 is operated on the iirst vertical Astep or' magnet 411 thereby switching the impulse circuit trom its normal to its alternate contact and over the alternate contact ot the slow-to-release relay 416 which was operated on the .lirst impulse. The olinormal switch 415 in operating also prepares a circuit 'tor the operation et the release magnet 417.

Vritter the last impulse ot the series, the brushes 418, 419 and 426 Will be elevated to the desired level and relay 416 will be deenergized thus switching the pulsing circuit to the rotary magnet 421, the circuiti'or which can be traced as follows: ground over contacts 469 o1 relay 462, contacts 412 oi? relay 466, contacts 413 oi relay 467, contacts -422 o'l the olii-normal switch 41-5, contacts 423 of relay 416, contacts 424 ot relay 425, Winding of sloW-to-release relay 426 and Winding of the rotary magnet 421 to grounded battery. As the last series ot impulses comesin the lower armature ot relay 466 drops back in step therewith and moves the brushes 418 and 419 into engagement with the desired subscribers line. When relay 426 operated it transterred the pulsing circuit from the normal contact et relay 425 to its own alternate contact 427.

[is soon as sloiwto-release relay 426 releases, it the called line idle, it closes a circuit tor the operation ot relay 462 which can be traced as t'ollows: battery (not shown), sleeve terminal 428 of the subscriberls line, brush 426, contacts 429 ot relay 426, contacts 436 et relay 425, upper Winding ot' relay 462, terminal 362 (Fig. 3), brush 341, right normal contact or' relay l 367, contacts 342 ot relay 319, conductor 346,

and ground at the right alternate contact ot relay 314. Relay 462 operates in this circuit and locks to ground at its contacts 436 over the linst traced circuit. Relay 462 in operating also connects the tip and ring conductors ol' the trunk through to conductors 431, 432 and places ground env the multiple test tcrininals ci' the seized subscribers line in the following circuit: ground, right-hand alternate contact of relay 314 (Fig. 3), conductor 346, contacts 342 ot relay 319, right normal contacts of relay 36?, brush. 341 and terminal 362, contracts 433 ol relay 462, contacts 436 ot relay 425, contacts 429 ot relay 426 and brush 426 which is in contact With test terminal of the called subscribers line. Further, relay 462 in attracting its lovverinost armature removesground troni the lower armature ot relay 466 and tran'ters this ground through a resistance 434 to hold relay 466 operated during the continuance of the connection in order that the ringing current circuit which extends through the upper alternate contact. of relay 466 Will not be broken at this point.

1t the called line is found lousy ground will be present on the test terminal 428 and before slow relay 426 has time to release, relay 425 which is also sloW-to-release Will be energized thus breaking the pulsing circuit branch at its contacts 424. When relay 426 finally releases, relay 425 locks up to ground on the conductor 446, this can be traced i'rom battery, Winding of relay 425, normal contacts 435 et relay 426, contacts 436 ot' relay 425 and to ground on conductor 446 as previously traced Whiclris supplied at the right-hand alternate contact of relay 314- ot' Fig. 3. Relay 425 in operating also connects Oround to operate the reverse relay 463 u'hicn circuit can be traced 'from battery, winding ot relay 463, contacts 437 oi relay 425 and contacts 438 et relay 426 to ground. Relay 463 new operates and reverses thel current flowing back over the trunlito the toll transmission vselector Fig. 3 where it operates polarized relay 348 bridged at the center ot the right-hand winding ot repeating coil 312 in series With resistances and 347.

lolar relay 348 in operating closes a circuit ior relay 357 which may be traced as follows: battery, Winding et relay 357, and contacts of relay 348 to ground at the lower alternate contact oi' relay 365. Relay 357 closes an obvious energizing circuit for reverse relay 311 which new operates and reverses and reduces the current in the loop circuit leading back toward the toll ofi'ice.

Relay 311 in operating connects ground overits outer left alternate contact` to the conductor 361 thereby causing relay 268 yin the pulse translating equipment (Fig. 2) to operate. Relay 268 in operating momentarily opens, at its contacts 265, the energizing circuit tor relay 168 in the operators dialing equipment (Fig. 1). Relay 168 in releasing closes a circuit for the energization ot relay 165. This circuit may be traced trom battery, left-hand alternate contactl of relay 116, right-hand Winding ot' relay 165, right-hand normal contacts et' relay 116, normal contacts ot relay 168, and to ground at the right-hand alternate contacts ot relay 115. Relay 165 operates in this circuit and disconnects battery at its right-hand normal contact thereby causing the release ot relay 166 in the cord circuit. The deenergization of relay 166 releases the dialing circuit and restores the cord to normal. `Wlien relay 268 operated and relay 262 released the bridge including resistance 267 across the trunlr circuit Was yopened at the alternate contacts of relay 262 but this bridge had previously been closed at the right-hand alternate contacts ot relay I268 When this relay operated, so that the selector circuitfvvas not affected. Relay 268 in operating also closed a circuit tor relay 217, which can be traced from ground, outer lett alternate contacts of lilo lll)

lili

lli?

relay 208, winding oi relav 217, normal contacts of relay 202, conductor 226, contacts 214 of relay 213, brush 218, conductor T (Fig. 3), upper left winding of repeating` coil 312, contacts 365 of relay 311, resistance 366, contacts 308 of relay 309, contacts 306 of relay 307 and lower winding ot relay 305 to grounded battery.

Relay 217 operates in this circuit and closes an obvious circuit for cut-through relay 203, which relay operates and locks up to ground on conductor 222, which ground is supplied at the left-hand alternate contacts of relay 311.

The operation of relay' 203 opens the circuit for relay 208 which relay releases and opens the bridge across conductors 226 and 230.

Relay 203, in operating, also disconnects the pulsing relay 202 from the trunk and extends the trunk through to the machine switching equipment.

`Relay 357, in operating, also connects ground through interrupter 353 to alternately operate busy bac-k relay 309, which relay, in turn, alternately opens and closes at its contacts 308 the loop circuit leading back to the toll oliice where it causes the supervisory relay 118 bridged across the cord to operate in step with the interrupter and flash lamp 119 as a signal that the called line is busy. In practice interrupter 358, for giving a linebusy signal, is arranged to interrupt the circuit at the rate of one hundred and twenty interruptions per minute.

If the subscribers line is not busy it is seized and relay 402 operates as belfore described. Relay 402, in operating opens at its contacts 401 the previously traced circuit for relay 329, which relay in turn releases and closes at its contact-s 367 a circuit yfor the operation of reverse relay 311, which may be traced as follows: battery, windingof relay 311, contacts 367 ot relay 329 and contacts 368 of olf-normal switch 323 to ground. When relay 329 releases it provides a substitute ground connection for the locking circuit of relay 407 so that this relay will not be deenergized when relay 402 is operated. This circuit may be traced as follows: grounded battery, lower winding of relay 407, contacts 410 of relay 407, conductor 441, terminal 364 and brush 350, Fig. 3, contacts 349 ot relay 319, conductor 327, contacts 328 of relay 329, contacts 330 of relay 309 and contacts 331 of relay 332 to ground.

Vhen relay V311 operates in thc circuit just traced it reverses and reduces the current flowing in the loop circuit extending back to the pulse repeating equipment of Fig. 2, which circuit includes the impulse relay 305 o the tolltransinission selector.

Relay 311 vin operatingl also connects ground at its outer left contacts to the lead 361 which causes relays 208, 217 and operate and the consequent release oi the dialing equipment of lJig. 1 as previously described in connection with the line busy condition. lWith relay 203 operated and locked up to ground on lead 222, the loop circuit is now extended back to the toll cord and current flowing in this loop circuit causes the steady operation of supervisory relay 118 and the consequent "hting ot supervisory lamp 119 which ser, as an indication to the operator that the building up of the connection has progressed properly to the subscribcrs line and that she can now start ringing` the called subscriber which is accomplished by depressing ringing key 120.

rlhe ringing current thus sent over the trunk from the cord circuit causes the operation ot alternating current relay 369 over an obvious circuit. Relay in operating, closes at its alternate contacts an obvious circuit for the operation o relay Relay 332, in operating, opens at its contacts 331 the locking circuit 'lor relay 407, which relay now releases and applies ringing current in series with its upper winding to the subscribers line. rihis ringing current is applied intermittently in a well known manner until the called subscriber removes his receiver lrom the hook, thereby causing an increase in the current vflowing in the upper winding oi relay 407, whereupon this relay again operates thereby disconnecting 'the ringing current and again locking the relay to ground over the control conductor 441, being assumed that the toll operator has restored the ringing lrey at the toll oiiicc, thereby releasing relays and 332, and reconnccting ground at contacts ol relay 332 to this control circuit. lt will, or' course,

be evident that only a short pulse olf ri ing current is necessary to cause the initial release of relay 407, after which the ringing is continued automatically from the connector circuit until the called subscriber answers and causes the reoperation olf relay 407. lt will be noted that the dialing key 107 can be restored at any time al'ter the dial has once been mored oli' normal, thus causing the closure oi a locking circuit for relay 106.

The extension of the tip and ring conductors of the trunk to the subscribers line by the operation of relay 407, when the called station S answers, operates relay 344 over a circuit including the windings ol coil contact-s of relay 329 and the right-hand windings of repeating coil 312. Talking current is lied to the calling subscribers line at the distant exchange in which the 'toll line 121 terminates. lVhen relay operates ii'V closes an obvious circuit for the energir/.ation of relay 309. Relay 309, in operating, supplies at its alternate contacts 370 ground 'for holding relay 407 locked, which circuit can C c. y

fill?) lil-ii he traced as follows: battery, lower Winding and contacts llO o'l' relay 407, conductors dell, terminal 2364.- (ltig. 3), brush 350, contacts Elli) of relay lll), conductor 327, contacts 328 o'l' relay 252) and to ground over pervisory lamp lll) which notifies n) era'tor that the subscriber has responded. By moving` the switchheol( up and down the subscriber at station lil can canse the super `Misery lamp lltl in 'the toll. cord to l'lash as is the manual practice or releasing the switches. 'll is is apparent from the ollowing description inasmuch as the relay flllis Vin circuit with the called suhscrihefs line and each time it attracts its armature relay i309 is energized which breaks the circuit lealini;` Mick to the supervisory relay .l l@ and at the same time places a bridge including; resistance 2371,. and contabts of relay :lll/l' across relay 05 to hold it opere/ted, thereby preventing' release et the switches.

'lhe operator can lie-ring the called. suhucrlloer itter he ln reglaced his receirer hy actuating)` the ringing` liey 120 thereby operutingg relay 369, which in turn, oaerates reiuy 532. l/Vhen relay 332 attracts its upper inner armature, ground is disconnected trein the control lead el), thereby peruiittiiigg relay lll? to release and to connect rinsing elm-ent to the subscriber-s line as l e described. lil/'hen the conversation is rshed and the subscriber' et station S has ieplaced his receiver, supervisory lamp 119 i lits as the manual telephone practice, which is 2, signal tor the operator to take down the connection and the plugv l0() removed from the jack 200. llelay (Fig. le released which causes the restoration el all the switches to normal as Will he de- ;ri bed later.

la, however, the operator removes the le subl; from the trunk jack While :zt :station fil luis the receiver olla the noel; relayY 305 which controls the re.

olE tlij itelies nn' tained energ Lied the circuijy incliuliugi resistance ""ll., due tlie optA ated condition of relay Silit i lt' in building; up connection toll "nsn'iission selector (Fig. il) encounters a lnisy trunk group lendingl to the connector' (llie. 4;), a circuit change is brought about 'te tiash the supervisory lump llt? at a rete drlf'erent trom that caused hy .tindn 5; tlie desired line lnisy which will now he dcsi ".'ilie l more in detuil.

.ln the case above described. o1" :ill trunks ivtween the toll ('rnnsniission selector and lso connector heing busy, switch 32E? would have heen operated upon the movement el r-x-f ,i contarle Sla( et relay the selector to its eleventh seconeary posi tion, thereby closing a circuit for relay 59 which can he traced es follows: groundel battery, winding el? relay 35.1, contacts a oit relay 33'? and over conductor 373 et rela;I 305 to ground.

Relay 359 in cpu-ating closes zin olniieus energizing circuit for relay Sli wliicn in operating` reverses and reduces the (nn-rent going` hachY to the nilse trfnisletinel equip ment of Fig. 2 ane also applies gronnd te conductor n2 r3 he'tore eescrilier14 in connection with th llusjf suhscril,... line.

Relay 359 in operating` also connects ground through interruptei. S273 te operate relay 309 which relay is alternately operated and releesed in step with the interrupter and flashes the supervisory lamp lli) as he'tore described, the only difference heine` that interrupter 3273 is arranged to hreali the circuit ot relay 809 :it the rate ot sixty Vinsteud o'l" one hundred and twenty times per minute as was the case with interrupter 2358 which was employed in the case ot the l i n e lousy condition.

The oprater in receiving` such a paths lnisy signal disconnects ne betere described und the sui telles return to normal.

lt Will `new lie z ssumed that the called :Tulisrriberis line was reached and Yfound idle and the culled subscriber answered the Call und :it the eenipletien et the conrmfsation hung; up hr. on the super- Visory lmnp lf) uns stf.` l' l e signal to the oper-atar ie called sul)- ecriber hed finished lt will further be assunii l that upon ;eceithis l tlie jar-l .tor the pinpe'i-:C of hreall. down the connection. Under these conditions relay 305 will release, which, in turn, will release relay lelay f1, in releasing, opens at its other le'l't armature contacts the connection 'tor the sleeve conductor 3l. ing hack over the contacts ot '.tch @l Winding or relay 2li-, norn'ial contacts (l` et the rotary magnet SM, contacts ot the ell-nor nml switch @Bl and WindinsA hy the l 'whereupon relay' i2 relay l ground Afrom cono relay ll-l; rc-

nie net 371- euerg P ufhicli ce.. he tra -i grounded hat# teli-y, vinding et ma l v y 1 s 376 ot contacts il switch 8c3,

1 e,- fl and 15 o relay :c te ground. lielay energized in parallel with magnet S74:

and opens at its right-hand normal contacts the circuit tor test brush Sil through the restoration operation. Relay 30T when energized also locls itself up at its lett-hand alternate contacts in a circuit including the contacts 376 oli the switch 323, which. switch will he opened when the selector is restored to norn'ial.

'lhe removal of ground from the test brush causes relay to release, which in turn cai es relay lll@ to release, which relay in retracting its lower armature completes a circuit 'tor release magnet il? which can be traced troin grounded battery through the winding ci magnet elle", contacts lill et switch 4.15, contacts Ltill ot relay 407, contacts l2 ol relay 00 and contacts Ll-09 or relay 402 to grouml. When the connector in restoring reaches its normal position switch llo is opened.

`When the toll transmission selector switch fb" returns to noi i i Imal, switch 323 is e. the eby removing 1nd at its contacts S to rilease relay Sil which relay in releasing 'omoves ground from conductors 361 and 222, thereby causing the dcencrgircation or relay 203, which relay in releasing disconnects the jack trom the trunk conductors 226 and() and reconnects relay 202 across the tip and ring springs ot the jack.

lt will be observed that throughout the building up ot the connection, battery was supplied .trom the dial 109 of the cord circuit tor operating the pulse translating relay 202 at the machine switching ollice, which relay in turn controlled the usual pulsing circuit and that when the dial was standing in its normal position, the trunk between the toll oliice and the machine switching ollice was dir y, that is, tree from battery.

That is claimed is:

1. In a telephone system, an operators position, a trunk circuit extending therefrom to an automatic exchange and having normally no connections to battery or ground, a cord circuit at said operators position tor connecting with said trunk circuit, a sender circuit including a source or dialing current adapted to be switched into connection with said cord circuit to transmit current pulses over said trunk circuit from said source corresponding to the desired setting ot a switch in said automatic exchange, and means in said trunk circuit at the automatic exchange end thereof responsive to said pulses to control the setting of said switch.

2. In a telephone system, an operators position, a normally dry trunk circuit extending therefrom to an automatic exchange, subscribers lines terminating in said exchange accessible to said trunk circuit, a cord circuit at said operators position for connecting` with said trunk circuit, a sender circuit including a source of dialing current adapted to be switched into connection with said cord circuit to transmit current pulses from said source over said trunk circuit corV responding to the desired setting of a switch at said automatic exchange tor connecting said trunk circuit with one of said subscrib ers lines, means including a relay, associated with said trunk circuit at said automatic exchange responsive to said pulses -to control the setting of said switch, and means for disconnecting said relay from said trunk circuit when the desired subscribers line is seized by said switch.

3. ln a telephone system, an operator?-V position, a normally dry interollice li-unl( circuit extending therefrom to an automatiil exchange, an automatic switch thereat acfcessible to said trunk circuit, a plurality ot other trunk circuits extending from said automatic switch to certain other switches, a cord circuit at said operators position for connecting with said interol'lice trunk eircuit, a sender circuit including a source ot dialing current adapted to be switched into connection with said cord circuit to trans-- mit current pulses over said interoliice trunk circuit corresponding to the desired setting of said lirst mentioned switch for connecting said interol'licc trunk circuit with one o'l" said plurality ot other trunk lines, means including a relay associated with said interotlice trunk circuit at said automatic exchange responsire to said pulses to control the setting of said switch into engagement with one ot said plurality of other trunks, and means tor disconnecting said relay from said interoliice trunk when all of said plurality ol other trunks are found busy by said first mentioned switch.

a. A telephone system, an operators position, a normally dry trunk circuit extending therefrom to an automatic exchange, subscribers lines terminating in said exchange accessible to said trunk circuit, a cord circuit at said operator-s posit-ion for connect-- ing with said trunk circuit, an operator con-- trolled sender circuit including a source of dialing current adapted to be switched into connection with said cord circuit for transmitting current impulses ilrom said source ever said trunk circuit corresponding to the desired setting oit a switch at said automatic exchange for connecting said trunk circuit to one of said subscribers lines, means including a relay associated with said trunk circuit at said automatic exchange responsive to said pulses to control the setting of said switch, a signal device associated with said cord circuit, and automatic means for disconnecting said relay from said trunk, connecting said trunk with said automatic swich, disconnecting said dial from said cord circuit and for actuating said signal device when the desired subscribers line is seized or when an intermediate paths busy condition is encountered.

lill) 5. A telephone system, an operators position, a normally dry trunk circuit extending therefrom to an automatic exchange, subscribers lines terminating in said exchange accessible to said trunk circuit, a cord circuit at said operator-s position for connecting with said trunk circuit, an operator controlled sender circuit including a source of dialing current adapted to be switched into connection with said cord circuit for trans mitting current impulses from said source over said trunk circuit corresponding` to the desired setting of a switch at said automatic exchange tor connecting said trunk circuit to one oi? said subscribers lines, means including a relay associated with said trunk circuit at said automatic exchange responsive to said pulses to control the setting oi said switch, a signaling device associated with said cord circuit, and automatic means for disconnecting` said relay from said trunk, connecting said trunk with said automatic switch, disconnecting said dial from said cord circuit and for actuating said signaling device in one manner when an intermediate paths busy condition is encountered, in another manner if the desired subscribers line is found busy and in a third manner when the desired subscribe1."s line is seized.

6. In a telephone system, an operators position, a trunk circuit extending there from to an automatic exchange and having normally no connections to battery or ground, an operators dial circuit including a source of current adapted to be connected to said trunk to transmit pulses of current thereover from said source, and a relay at said exchange associated with said trunk circuit and controlled by said pulses to in turn control the operation of a selector switch at said exchange.

7. In a telephone system, an operators position, a trunk circuit extending therefrom to an automatic exchange, an operators dial circuit including a source o current adapted to be connected to said trunk to transmit pulses of current thereover from said source, a selector switch at said automatic exchange associated with said trunk, a relay at said exchange associated with said trunk circuit and controlled by said pulses to in turn control the operation of said selector switch at said exchange, subscribers lines accessible by said selector switch and `for the establishing of a connection between a called subscriber and said trunk circuit, and means controlled by said switch when it comes to rest on a called subscribers line for disconnecting said relay from said trunk cir cuit.

ln testimony whereof, I have signed my name to this specification this 10th day of June, 1924.

JOHN F. TOOMEY. 

